Such an electrode lead is comprised of an elongated body, the exterior of which is comprised of an insulating material, such as, for example, silicone or polyurethane. The body has a proximal end and a distal end. Situated on the proximal end is at least one plug which can be connected to a connector—which is usually a socket—in the connector housing of the implant. The plug can be standardized and can be designed according to one of the standards, namely, IS-1, IS-4, or DF-1. Each of the electrically active contacts of the plug is electrically connected to an electrical supply lead which, in turn, is usually electrically connected at the distal end thereof to an electrically active surface (also referred to as “electrode pole” or “electrode”) which is located on the distal end or in the vicinity thereof. Each of the connecting lines is insulated. The electrically active surfaces are used to induce electrical therapy at the body part to be treated, such as, for example, in or on the heart, in or on the brain or on nerves, or to receive measurement signals for diagnostic purposes.
Electrode leads typically comprise at least one preformed and/or stiffened section of the electrode lead body. These preformed or stiffened sections are used for a plurality of purposes. For instance, the attachment properties of the electrode leads in the area to be treated can be improved substantially by the use of certain shapes, such as, for example, the shape of a “J”, a helix, an “S”, or an omega. In the case of electrode leads disposed in the coronary sinus, in particular, the morphology of the vascular wall limits the attachment method to that of securing a section of the electrode lead body in the vessel. The maximum lateral extension of the electrode lead in the preformed and/or stiffened section is predetermined by the diameter of the vessel intended for use as the application site, and is approximately 8 mm for a coronary sinus electrode lead.
Furthermore, preformations of an electrode lead section are known which are designed especially for coronary sinus electrode leads and electrode leads that are used, e.g., to stimulate the high septum, and which simplify the placement of the electrodes at certain points. For example, introducing a coronary sinus electrode lead into the coronary sinus is complicated in some ways and requires a great deal of practice.
A conventional electrode lead having the shape of a “J” is shown in FIG. 1. The design thereof is characterized by an electrode body 110 which is preformed in the distal region in the shape of a “J”. The electrode comprises, on the proximal end thereof, a bipolar plug which is not depicted and can be designed according to, for example, the IS-1 standard, and comprises on the distal end thereof two electrode poles in the form of a head or tip electrode pole 120 and a ring electrode pole 130, and a mechanism for electrode attachment 140.
FIG. 2 shows the design of a known “J”-shaped electrode lead. It comprises an outer insulation 210 made of silicone or polyurethane (“PU”), for instance. An outer supply lead coil 220 for the connection of ring electrode 130, an inner insulation 230, and an inner supply lead coil 240 for the connection of tip electrode 120. Since the “J” shape in the electrode body is preformed, an inner lumen 250 for accommodating a guide wire is required for implantation, in order to straighten the electrode as it is being inserted into the atrium, and primarily to enable the attachment thereof.
The preformed and/or stiffened section of such a shaped electrode lead typically comprises an elastically preformed and/or stiffened preformation and stiffening structure designed as a core of tempered MP35N steel, for instance. The elasticity of the lead is generally predetermined by the suitable selection of the strength and material handling conditions of the steel core such that it can be straightened easily by the guide wire used for implantation. Such a core is known from European Patent No. EP 0 951 920.
This known preformation and/or stiffening of the electrode lead has a plurality of disadvantages. For example, the electrode leads according to the prior art require a guide wire for implantation in order to advance the preformed and/or stiffened section to the implantation site without damaging the vessel. For this purpose, an elongated guide wire is slid into the above-mentioned inner lumen, thereby straightening the preformed and/or stiffened section. However, this lumen substantially limits the design freedom, since electrode leads must be designed with substantially larger diameters. Such electrode leads can therefore not be used arbitrarily in any vessel.
Furthermore, it has proven disadvantageous that an electrode lead must have a certain minimum stiffness in the region of the preformed and/or stiffened sections to support the function thereof as an anchoring means or insertion aid. This relative stiffness causes permanent stressing of the tissue at the attachment site of the electrode lead in, for example, the endocardium or the coronary arteries. Greater stimulation thresholds are induced as a result, thereby possibly increasing the risk of dislocation or perforations of the surrounding cardiac muscle, which have been documented in a few cases.
A problem addressed by the present inventive disclosure is therefore that of eliminating the disadvantages of the electrode leads made known in the prior art, and of improving an electrode lead such that it can be inserted without the use of tools and can be implanted without harming the surrounding tissue.
The present inventive disclosure is directed toward overcoming one or more of the above-identified problems.